Oleo gear



April 20, 1937- h c. v. JOHNSON 2,077,934

` OLEO GEAR l Filed Sept. 17, 1951 I -f 5- 46 6 ii l 62 l l I." 66 L 68il 70 l 72 yg 2 48 74 li i 50 0 is; 0 `5Z- 54 6.,. INVENTOR. l

58 .CARLV.JoHN5oN I BY / 60 v I ATTORNEY -fPfe'med Apr. 2o, i937 PATENTOFFICE OLEO GEAR Carl V. Johnson, South Bend, Ind., assignor to BendixAviation Corporation, South Bend, Ind., a corporation of DelawareApplication September 17, 1931, Serial No. 563,453

12 Claims.

This invention relates to shock absorbers and more particularly to shockabsorbing struts for aircraft.

Shock absorbing struts are extensively used in 5 landing gears forairplanes. Various types have pneumatic, hydraulic, and combinedpneumatic 10 and hydraulic. 'I'he present invention has to do with thelatter type.

Broadly, the invention comprehends a pneumatic hydraulic shock absorbingstrut designed to 20 provided with an oric'e.

ports an internal cylinder having one end in comextended position.

An object of the invention is to provide a shock rut having relativelyfew parts which may be easily and quickly assembled.

35 Another object of the invention is to provide a shock strut in whichstandard tubing may be used for certain compon` `1t parts.

Another object ofthe invention is to provide a shock strut having a twopart cylinder only 40 one of which needs to be nished internally.

Another object of the inventionis to provide a shock strut of thecombined pneumatic hydraulic type in which the air chamber is as largeas the oil chamber, so that lower pressures may 5 be used.

A feature of the invention is to provide a shock strut comprising aiixed and movable member and means for bracing the ked member includingdrag struts and means for securing the drag 5 struts to the xed member.

Another feature of the invention is a. shock v strut in which straighttubing is used for the telescopic members of the structure.

Another feature of the invention is a shock strut including a two partcylindrical chamber and an apertured diaphragm forming a union betweenthe parts.

Another feature of the invention is a shock strut including a pistonhaving a skirt and packing material carried on the skirt serving as acushion when the strut is in the fully extended position.

Other objects and features of the invention will appear fromthefollowing description taken in connection with the drawing, in which:

Figure 1 is a longitudinal sectional viewof a shock strut completelyextended, and

Figure 2 is an enlarged view illustrating the strut partially collapsed.

Referring to the drawing formore specic details of the invention, Irepresents a cylinder closed at one end by a cap l2 provided with aclevis I4. Ihis clevis provides a suitable means through which thecylinder may be secured to the 'fuselage of an airplane. Arranged on thewall of the cylinder adjacent the cap is a reinforcing plate I6. Theplate and the cylinder are bored and threaded as indicated at I8 and 20to receive respectively a plug 22 which may be removed for the purposeof introducing oil into the cylinder,

l and a valve 24 through which air may beA introduced into the cylinder.cylinder I8 has threaded or otherwise secured therein one end of asleeve 26.

As shown, the sleeve 26 has a circumferential ilange 28 abutting one endof the cylinder |Il.- This ange has the same diameter as the cylinder sothat when the sleeve is threaded in the cylinder a smooth unbrokensurface is presented. The sleeve A26 has therein a diaphragm 30 providedwith an orifice 32. 'Ihe diaphragm 3l) supports a chamber or cylinder 34arranged concentrically within the chamber I0 in direct communicationwith the orice in the diaphragm. The chamber 34 has on one end a iiange36 which may be riveted or otherwise lsecured to the diaphragm and theother endvof the cylinder 34 is provided with a cap 38 having an orice40 controlled through a iiap valve 42, and in the baseof the cylindernear the end secured to the diaphragm are spaced vents 44. l

'I'he sleeve 26 has threaded or otherwise. secured thereto one end of acylinder 4,6 abutting the circumferential ilange 28. 'Ihis cylinder hasltted into its other end a ring 48 secured against displacement by acylinder head or collar U having lugs 52 to which may be secured dragstruts, not shown. 'I'he collar 50 has a triple diametral bore. Thelarger bore is threaded to receive the cylinder 46 and between thelarger bore and the The other end of the 2 intermediate bore is ashoulder 54 abutting the cylinder 46 and the ring'48. The ring 48 alsomay serve as a reinforcement for the threaded end of the cylinder 46,and prevent collapsing or buckling thereof.

Positioned for reciprocatlon in the smaller bore of the collar is apiston rod including a tubular having secured tothe outer end thereof acap 58 provided with a clevis 60 for the attachment of an axle or otherparts associated with the wheels of the airplane. Suitably secured tothe inner end of the member 56 is a piston head 62. As shown, the pistonhead is fitted snugly within the cylinder 46, and the head carries ametering pin 64 adaptable for cooperation with the orifice 32. Thepiston head 62` has a skirt 66 arranged concentrically, so as to providein "conjunction with the cylinder 46 a packing gland 68 for thereception of suitable packing material 10. The

packing material is carried on the skirt and is retained againstdisplacement between the head 62 and a packing retaining ring 12 sleevedon the skirt and held against displacement by a collar member 14threaded on the s The packing material provides a suitable leak proofconnection' between the piston and the cylinder and due to its elasticycharacteristics and its annular length also provides an ideal cushionfor the piston on the return stroke and when the strut is in the fullyextended position. Any packing material may be used, such as rubber orrubber compositions, leather and the like, it being understood that thedamping liquid and packing material must be so chosen that one does notaifect the other.

Assuming that the strut is filled with suitable hydraulic fluid and airor gas, the strut will under impact of landing cause the hydraulic uidto be forced through the orifice in the diaphragm past the metering pininto the rise of the liquid and this combined resistance offered by thecompression of the air or gas and the now of liquid.

On the compression stroke the liquid passes freely through the flapvalve on the inner chamber into which the metering pin moves and on thereturn stroke the a-p valve closes due to the pressure of the compressedair or gas thus forcing the liquid to return through the small vents ororifices near the base of the inner chamber. This prevents suddenrebound that would otherwise result.

Although this invention has been described in connection with certainspecific embodiments, the principles involved are susceptible ofnumerous other applications that will readily occur to persons skilledin the art. The invention is, therefore, to be limited only as indicatedby the scope of the appended claims.

Having thus described the the invention, what to secure by Lettersvarious features of I claim as new and desire Patent is:

1. A shock absorbing strut comprising a two A part cylinder and a unionfor the parts including a sleeve having a diaphragm and acircumferential ange.

2. A shock absorbing strut comprising a two part cylinder and a unionfor the parts includ-V ing a sleeve having a diaphragm provided with anorifice, and a circumferential flange of the same diameter as thepartsof the cylinder.

3. A shock absorbing strut comprising a two part cylinder, a union forthe parts including a' the upper chamber, where the air or gas will becompressed by sleeve, a diaphragm in the sleeve provided with anorifice, and a circumferential flange forming shoulders for the adjacentends of the parts.

4. A shock absorbing strut comprising a cylinder, a diaphragm in thecylinder having an oriflce, a piston positioned for reciprocation in thecylinder, comprising a head on the piston fitted cylinder, and a skirthaving a smaller diameter than the head, packing material on the skirt,means for retaining the packing material on the skirt, a collar on thecylinder embracing the piston and a-metering pin carried by the pistoncooperating with the orifice in the diaphragm.

5. A shock absorbing strut der, a diaphragm positioned therein, havingan orifice, a piston positioned for reciprocation in the cylinder, ametering pin carried by the piston for cooperating with the orifice, andmeans carried by the piston providing a cushion for the piston on thereturn stroke and when the strut is in a fully extended position.

6. A shock absorbing strut comprising a cylinder, a diaphragm in thecylinder having an orifice, a piston having a head positioned forrecipeomprising a. cylinh rocation in the cylinder, a piston rod, ametering pin carried by the piston for cooperating with the orifice, acollar on the cylinder embracing the piston rod and means interposedbetween the piston head and the collar providing a cushion for thepiston on the return stroke, and when the strut is in a fully extendedposition.

'7. A shock absorbing strut comprising a two part cylinder, a sleeveconnecting the parts, a diaphragm. in the sleeve having an orice, apiston and piston rod positioned for reciprocation in the cylinder, ametering pin carried by the piston adaptable for cooperating with theorifice, a collar on the cylinder embracing the piston rod, means forsecuring the collar against displacement including means for bracing thecylinder against movement, and means carried by the piston providing acushion therefor on the return stroke land when the strut is in thefully extended position.

part cylinder, a sleeve connecting the parts, a diaphragm in the sleevehaving an orifice, an internal cylinder supported by the diaphragmhaving one end communicating with the aperture in the diaphragm, a valveon the other end of the internal cylinder, a piston and piston rodpositioned for reciprocation in the cylinder, a metering pin carried bythe piston arranged for cooperating with the oridce in the diaphragm, acollar on the cylinder embracing the piston rod, means for retaining thecollar against displacement including means for bracing the cylinderagainst movement, and means on the piston tending to cushion the pistonon the return stroke and when the strut is in the fully extendedposition.

9. In a shock strut. a cylinder, a piston, a cylinder head threaded onthe outside of said cyl- Inder and a piston rod passing through saidcylinder head, packing means on said piston rod within said head, meanson said rod for limiting packing, and snugly fitting the interior ofsaid cylinder and resting on said head, said collar adapted to compressand reduce the axial length of saidv packing to absorb shock when saidpiston is driven forcibly toward said head.

10. In a shock strut, a cylinder, a piston, a cylinder head threadedonthe outside of said cylinder, a piston rod passing through said cylinderhead, a loose retaining ring on said piston rod topin housing secured tothe upper side of said diagether with al collar against which said ringmay phragm surrounding said orice having a onerest, said ring and collarbeing Within said cylway valve in the top thereof, and a bleed port ininder, stuing material. between said retaining the lower side wallthereof.

ring and piston head, and an annular collar snugly 12. A shock absorbing'strut comprising a cyl- 5 tting Within said vcylinder and seated on theinder,animpervious diaphragm save fora central head adapted to engagethe outer periphery of orifice centrally located therein, apiston andpissaid retaining ring to compress said packing upon ton rod arrangedfor reciprocation in the lower extreme piston movement toward said head.portion of'said cylinder, a metering pin secured 10 11.A A ShOCkabsorbing Strut Comprising a Cylto said piston and coacting with saidorice, and 10 inder, a diaphragm centrally located therein havalmetering pin housing secured to the upper side ing a, central orice, a.piston and piston rod arof said diaphragm surrounding said orice havingranged for reciprocation in the lower portion of a one-Way valve in thetop thereof, and a bleed said cylinder, a metering pin secured to saidpisport in the lower side wall thereof.

ton and coactlng with said orifice, and a metering CARL V. JOHNSON. 15

